Cast aluminum textile beam

ABSTRACT

A textile beam construction consisting of a barrel and a cast aluminum head secured to each end thereof. Each head has a hub portion with a cylindrical surface extending axially of the beam and has a retaining surface extending outwardly in radial relation to the cylindrical surface. An annular concave surface or fillet is formed on each head at the junction between the cylindrical and retaining surfaces, and the ultimate strength of each head is materially increased by providing residual compressive stress in the material forming the annular fillet. This fillet is initially formed on a radius greater than the desired finished radius, and a rolling operation is carried out on the fillet surface to apply a compressive force which reduces the radius to finished dimension and creates the residual compressive stress in the cast material of the head forming the fillet surface.

United States Patent [1 1 OMalley Oct. 21, 1975 CAST ALUMINUM TEXTILEBEAM Arthur S. OMalley, Charlotte, NC.

[73] Assignee: Hayes Albion Corporation,

Charlotte, NC.

22 Filed: Sept. 13, 1973 21 Appl. No.: 397,085

[75] Inventor:

Primary Examiner-George F. Mautz Attorney, Agent, or FirmFarley, Forsterand Farley [57] ABSTRACT A textile beam construction consisting of abarrel and a cast aluminum head secured to each end thereof. Each headhas a hub portion with a cylindrical surface extending axially of thebeam and has a retaining surface extending outwardly in radial relationto the cylindrical surface. An annular concave surface or fillet isformed on each head at the junction between the cylindrical andretaining surfaces, and the ultimate strength of each head is materiallyincreased by providing residual compressive stress in the materialforming the annular fillet. This fillet is initially formed on a radiusgreater than the desired finished radius, and a rolling operation iscarried out on the fillet surface to apply a compressive force whichreduces the radius to finished dimension and creates the residualcompressive stress in the cast material of the head forming the filletsurface.

4 Claims, 3 Drawing Figures CAST ALUMINUM TEXTILE BEAM SUMMARY OF THEINVENTION This invention relates to an improved construction for atextile beam or spool having a cast aluminum head secured to each end ofa central portion or barrel, and to an improved method for manufacturingsuch a head of cast aluminum to provide the desired amount of ultimatestrength.

Conventionally, a textile beam or relatively large spool consists of acylindrical barrel to which a pair of heads are secured, each headhaving a hub with a cylindrical surface portion at one end of the barreland extending axially thereof, and having a retaining surface portionextending radially outward of the hub. For the larger sizes of beams orspools used in the textile industry, such as the so-called tricot beamsemployed for fine denier nylon yarn, the heads of the beam have beenmade as aluminum forgings, and while this adds considerable expense tothe article, no other type of construction has been known whichsatisfies the requirements for minimum weight and for sufficientstrength to withstand the high loads imposed when the beam is wound withyarn. Beams or spools have been manufactured with heads made of castaluminum, but only in smaller sizes and for light duty service becauseof the relatively low ultimate strength of this type of construction.

Recently it was thought possible, in view of improved techniques andquality controls available in the aluminum founding art, to manufacturea tricot beam with cast aluminum heads at a cost considerably below thatrequired for the same beam with forged aluminum heads. Attempts to dothis did not prove successful. Repeated test failures were encounteredwith cast aluminum heads at loads well below the ultimate strengthrequired for safe and satisfactory service. For a nylon tricot beam,having heads 30 inches in diameter, a minimum breaking strength of275,000 lbs. is desired, which is an easily attainable figure with theforged construction and which seemed to be attainable in a castconstruction. With cast heads however, it was found by test thatfailures could occur at loads less than half the desired breakingstrength, and even though an average figure for the ultimate strength ofthe cast head beam was higher, it was still well below that necessaryfor safe operation in service, where the failure of the head of a beamcan be a very dangerous and costly accident due to the magnitude of theforces involved.

The present invention provides a beam construction in which the forgedaluminum heads can be replaced at an appreciable saving in cost withheads made of aluminum castings and having an ultimate breaking strengthsuitable for tricot and other relatively high loading applications. Theinvention also provides a method for commercially manufacturing a castaluminum head for a beam or spool having a marked increase in ultimatebreaking strength in comparison with such a cast aluminum head producedwithout the use of this method.

In the textile beam construction of the invention, which includes acylindrical barrel and a head secured to each end of the barrel, eachhead has a hub with a cylindrical surface forming a continuation of thebarrel and has a retaining surface extending radially outward from thecylindrical surface. Each head consists of an aluminum casting providedwith an annular concave surface forming a fillet at the junction betweenthe cylindrical and retaining surfaces thereof, and the cast aluminummaterial forming the annular fillet has a residual compressive stressprovided therein when the beam is in an unloaded condition. Preferably,this residual compressive stress is on the order of 25,000 lbs. persquare inch.

The invention provides a method for making a cast aluminum head for atextile beam or spool in which the concave fillet formed at the junctionbetween the cylindrical and retaining surfaces of the head is initiallyformed with a radius having a dimension in excess of that desired forthe finished dimension of the radius of this fillet, and a compressiveforce is applied to the annular fillet surface to reduce the dimensionof the radius thereof to the desired finished dimension and to therebycreate the residual compressive stress in the material of the headforming the annular fillet surface.

Preferably the method is carried out by employing a roller provided witha convex peripheral profile formed on a radius having the dimension ofthe finished radius of the fillet; and, this roller is additionallyprovided with marginal portions bordering the convex peripheral profile,which marginal portions are at right angles to each other and engage thecylindrical and retaining surfaces of the head during the rollingoperation to limit the action of the compressive force applied to thefillet surface.

Other features and advantages of the invention will appear from thedescription to follow of the representative embodiment thereof disclosedin the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation showing the principalcomponents of a textile beam or spool and illustrating the forces towhich these components are subjected when a material is wound thereon;

FIG. 2 is an enlarged sectional detail taken through a head of a beamconstructed in accordance with the invention and showing the junctionbetween the hub and yarn retaining surface portions thereof; and,

FIG. 3 is a sectional detail similar to FIG. 2 illustrating a method forthe manufacture of a cast aluminum beam head according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The embodiment to be describedherein illustrates an application of the invention to the constructionof a textile beam, but it will be appreciated that the principlesinvolved can be applied to the construction of other types of largespools.

A conventional textile beam 10, schematically illustrated in FIG. 1,consists of a cylindrical barrel 12 whose axis defines the axis of thebeam, and a head 14 suitably connected to the barrel at each end 15thereof. Each head 14 has a hub 16 with a cylindrical surface 17extending axially of the beam to form a continuation of the cylindricalbarrel 12, and has a retaining surface 18 extending radially outward ofthe cylindrical surface 17.

When the beam 10 is wound with yam 19, compressive forces are imposedupon the barrel 12 as indicated by the arrows 20, and spreading forcesare imposed upon the retaining surfaces 18 of the heads as indicated bythe arrows 22. As a result of these forces, high tensile stresses arecreated at the junction between the cylindrical surface 17 and theretaining surface 18 ofeach of the heads 14, at which junction anannular concave surface of fillet 24 is conventionally provided. Mostbeam failures under yarn loading occur at this junction.

FIG. 2 gives an enlarged sectional view of the junction between thecylindrical surface 17 and retaining surface 18 of the head of a beamconstructed in accor dance with the invention. In this view, a portionof the barrel 12 is indicated in broken line together with a connectionbetween the hub 16 and the barrel 12 such as disclosed in U.S. Pat. No.3,317,160.

The head 14 shown in FIG. 2 comprises an aluminum casting provided withthe annular concave surface or fillet 24 at the junction between thecylindrical surface 17 and the yarn returning surface 18 of the head.The cast aluminum material which forms the annular fillet 24 has aresidual compressive stress provided therein, as indicated by the shadedarea 26, when the beam is in an unloaded condition.

FIG. 3 illustrates a preferred method for making the cast aluminum head14 of FIG. 2. A concave annular fillet 24a is formed at the junctionbetween the cylindri cal surface 17 and the retaining surface 18 of thehead on a radius having a dimension in excess of that desired for thefinished dimension of the radius of the fillet 24 of FIG. 2. Then, acompressive force is applied to the annular fillet surface 24a to reducethe dimension of the radius thereof to the desired finished radius ofthe fillet 24 and to thereby create the residual compressive stress inthe area 26. In FIG. 3, the application of compressive force to thefillet surface 24a is performed by employing a roller 28 having a convexperipheral profile 30 formed on a radius having a dimension conformingto the desired finished radius of the fillet 24. The roller 28 is alsoprovided with marginal portions 32 and 34 bordering the convexperipheral profile 30 thereof, which marginal portions are at rightangles to each other. When the rolling operation is carried out under acompressive force indicated by the arrow 36, the marginal portions 32and 34 on the periphery of the roller 28 eventually engage the retainingsurface 18 and the cylindrical surface 17 of the head, respectively,thus limiting the action of the compressive force applied to the arcuatefillet 24a and insuring that the fillet is rolled to the desiredfinished radius.

The invention will be further described with reference to testsperformed on beams for nylon tricot applications with cast aluminumheads 30 inches in diameter. In one test, some of these heads wereprovided with a fillet 24 machined or cut to a standard radius of 0.093inch. Other samples were made with a fillet 24a cut to a radius of 0.125inch and then rolled to the radius of 0.093 inch by the method shown inFIG. 3, applying a compressive force on the order of 2,500 lbs. Testbeam specimens were made, some of these specimens being provided withthe heads having the cut fillets and other specimens being provided withheads having the rolled fillets.

Static load tests showed that the beams with cut fillet heads failedbetween 160,000 and 304,000 pounds with an average failure load of243,000 pounds. Beams with rolled fillet heads failed between 255,000and 349,000 pounds with an average failure load of 321,000 pounds. Onthe average, the beams with rolled fillets had an ultimate strengthapproximately one-third greater than the beams with cut fillets; also,all beams with rolled fillets failed above a load of 225,000 pounds withfigure was established as a minimum test value for satisfactorycommercial production. In contrast, failures of beams with cut filletsoccurred below this minimum test value in sufficient number to make thecut fillet construction not feasible for commercial production becauseof the high scrap losses that could be expected. In another testconducted, two 30 inch nylon tricot cast aluminum heads, one with a0.093 inch radius cut fillet and the other with the fillet cut to a0.125 inch radius and then rolled to a 0.093 inch radius, were eachinstrumented at the fillet with 8 foil type resistance strain gages. Thetwo test heads were loaded, against an 18.5 inch diameter load ring,using a 1.2 million pound capacity Baldwin load test machine todetermine the comparative effect of fillet rolling on fillet strainunder load, at rest after load and at failure. Static strain readingswere taken under load at 25,000 pound intervals from 0 to 150,000pounds, and at rest after this load cycle. Dynamic strain was thenrecorded continuously from zero load to failure. At 150,000 pounds load,the cut fillet showed plus 6170 micro-strain, the rolled fillet plus5650 micro-strain, or 520 micro-strain less. The peak fillet strain atrest after 150,000 pounds load, or the zero shift, showed the cut filletwith plus 1303 micro-strain, the rolled fillet plus 149 micro-strain, oran 88.6 percent reduction in the zero shift. The failure load for thecut fillet was 284,000 pounds, for the rolled fillet 370,000 pounds or a30 percent increase in strength. Peak fillet strain at failure for thecut fillet was 18,750 micro-strain, for the rolled fillet 24,000microstrain or an increase of 5250 micro-strain. The large differentialin peak fillet strain at rest after load, or zero shift, gives a verydefinite indication that fillet rolling has altered the fillet stresslevel prior to loading. The higher strain at failure in the rolledfillet leads to the conclusion that the fillet rolling operation doescreate residual compressive stress, and that it is of the order ofmagnitude of 5,000 micro-strain.

Further investigation of the residual compressive stress was made byx-ray stress analysis, and indicated a residual compressive stress ofapproximately 29,000 p.s.i. in the area of the fillet formed with therolled radius of 0.093 inch as described herein. A fillet formed withthe cut radius of the same dimension was found to contain no detectableresidual compressive stress.

The foregoing tests demonstrate the significant increase in ultimatestrength obtained in a cast aluminum beam head made with the rolledfillet by the method illustrated in FIG. 3 and described herein. Thesetests also prove that the rolling operation creates a residualcompressive stress in the cast aluminum material of the head forming therolled fillet 24.

While other techniques, such as shot peening could be employed to applythe compressive force to the fillet surface 24a necessary to reduce theradius thereof to the final dimension of the fillet 24, the rollingoperation disclosed is presently preferred because of the ease withwhich it can be controlled. This method makes the production of textilebeams with cast aluminum heads commercially practical, and with aconsiderable reduction in cost as compared with the conventionalconstruction using forged heads.

I claim:

1. A textile beam or spool comprising a cylindrical barrel whose axisdefines the beam axis, and a head secured to each end ofthe barrel, eachhead having a hub with a cylindrical surface extending axially of thebeam is in an unloaded condition, said residual compres-.

sive stress being localized in that portion of the cast aluminummaterial which forms said annular concave surface.

2. A textile beam or spool according to claim 1 wherein said residualcompressive stress is on the order of 25,000 pounds per square inch.

3. A head for a textile beam or spool, said head having a hub with acylindrical surface, a retaining surface extending radially outward fromsaid cylindrical surface, and a concave annular fillet at the junctionbetween said cylindrical and retaining surfaces; wherein the material ofsaid head is provided with a residual compressive stress which islocalized at said concave annular fillet.

4. A head according to claim 3 wherein said residual compressive stressis on the order of 25,000 pounds per UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION PATENT NO. 3,913,863

DATED 3 October 21, 1975 INVENTOR(S) Arthurv s, O'Malley It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 4, line 1, "with" changed to read -which- Signed and Scaled thistenth Day Of February 1976 [SEAL] A! test:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofPatentsand Trademarks

1. A textile beam or spool comprising a cylindrical barrel whose axisdefines the beam axis, and a head secured to each end of the barrel,each head having a hub with a cylindrical surface extending axially ofthe beam to form a continuation of the cylindrical barrel and having aretaining surface extending radially outward from the cylindricalsurface of the hub; wherein: each head comprises an aluminum castingprovided with an annular concave surface forming a fillet between saidaxially and radially extending surfaces; and, the cast aluminum materialin each head is provided with a residual compressive stress when thebeam is in an unloaded condition, said residual compressive stress beinglocalized in that portion of the cast aluminum material which forms saidannular concave surface.
 2. A textile beam or spool according to claim 1wherein said residual compressive stress is on the order of 25,000pounds per square inch.
 3. A head for a textile beam or spool, said headhaving a hub with a cylindrical surface, a retaining surface extendingradially outward from said cylindrical surface, and a concave annularfillet at the junction between said cylindrical and retaining surfaces;wherein the material of said head is provided with a residualcompressive stress which is localized at said concave annular fillet. 4.A head according to claim 3 wherein said residual compressive stress ison the order of 25,000 pounds per square inch.